Technical Field
The invention relates to a fish stunning apparatus, comprising a fish feed-in device which is configured for conveying fish head first, a fish receiving space which is loadable with fish in the head first position by the fish feed-in device, a fish positioning device with a fish positioning means which engages on the fish head, which positioning means, for the purpose of stunning the fish, defines a temporary stop position of the fish in the fish receiving space, said stop position being releasable after stunning for discharging the fish, a stunning means for acting on the head-end region of the fish in its temporary stop position in the fish receiving space, a trigger device by means of which the temporary stop position is determinable and operation of the stunning means for acting on the head-end fish region can be activated, and a control device which for controlling operation is operatively connected to the fish positioning device, the stunning means and the trigger device.
The invention also relates to a trigger unit designed for installation in the fish stunning apparatus and to a method for activating a stunning means of a fish stunning apparatus.
State of the Art
A fish stunning apparatus of the type mentioned is disclosed, for example, in EP 1 908 353 A1. The apparatus is such that fish are fed in individually consecutively along the fish feed-in device, each fish arriving in a fish receiving space in the ventral position and with its head first. Located therein is a movably supported positioning and trigger abutment element of a trigger device. The fish head strikes under the fish's own weight against the trigger abutment element which is thereby moved along an activation path and as a result initiates the operation of a mechanical stunning means, namely a firing pin or similar stunning tool which strikes the skull of the fish head in order to stun the fish. The stunning tool is movable between a retracted and an extended position, namely the striking position. The trigger device and the stunning means are connected to a control device, namely a pneumatic circuit. This is also connected to a further positioning element which is controlled for holding the fish and for releasing the fish after stunning is complete. The fish pass through the fish stunning apparatus with a flow of water in order to pass the stunning apparatus.
WO 2012/020283 A1 discloses a fish stunning apparatus which is equipped with a mechanical stunning means, namely a striking tool, the position of which can be changed depending on the fish size. Such a known apparatus requires means for mechanically measuring and controlling the position of the stunning means. The apparatus is complicated to construct and positioning of the stunning means is not satisfactory.
A fish stunning apparatus is disclosed in GB 2 391 446 A which has a device for determining the head position in relation to the longitudinal direction of the stunning apparatus. The fish is conveyed continuously, a control device calculating the point in time for activating the stunning means and initiating a stunning stroke at the point of the calculated position of the fish. This known fish stunning apparatus must be operated with continuously conveyed fish and the activation time of the stunning tool requires a special calculation algorithm.